How many asbestos-related lung cancer deaths are there each year?

Lung cancer deaths caused by asbestos are clinically indistinguishable from those caused by other agents such as tobacco smoke. This means the number of cases cannot be determined by direct counting and must therefore be estimated.

Because of improving evidence, our "best estimate" of the annual number of asbestos-related lung cancers has been revised over the years from "about two lung cancer deaths per mesothelioma each year" before the early 1990s to "one or two" and then to "around one" more recently.

In the past our estimates have largely been based on comparisons of numbers of mesothelioma deaths in studies of groups of asbestos-exposed individuals with numbers of ‘excess’ lung cancers in those groups (how many more lung cancers were observed than would have been expected in the groups if there had been no asbestos exposure). Estimates produced on this basis have always been regarded as uncertain (and still are).

Recent research estimated the ratio of asbestos-related lung cancer deaths to mesotheliomas by developing a statistical model for lung cancer mortality within the British working population in terms of asbestos exposure and smoking habit [1]. This suggests a ratio in the range 0.7 to 1 – in other words rather fewer lung cancers than mesotheliomas. However, in view of the uncertainties "around one asbestos-related lung cancer per mesothelioma" is probably still a reasonable view.

Asbestos is a more potent cause of mesothelioma than lung cancer and smoking is thought to interact with asbestos exposure in the causation of lung cancer. Thus going forward in time the ratio of lung cancers to mesotheliomas is likely to fall, because the mesotheliomas will increasingly be generated by low exposure levels of asbestos that are less likely to cause lung cancer and because smoking levels have fallen since the 1960s (factors that, together, mean fewer lung cancers per mesothelioma).